For this breathing rig I started with a MSA Comfo classic half mask that I already had. This case worked out exceptionally well.
First thing was to remove all the hardware from the mask. This was quite simple just stretch the mask over the plastic parts and they pop right out.
The strap bracket is held in place with a single rubber pin. Just push this out of the strap bracket.
Now we have a nice rubber mask with three holes; one for a tube and two to plug.
For the plugs I dug out a hole saw and some acrylic scrap.
- Made four circles;
- sand them down (sharp edges galore from the hole saw).
- Combine two circles with a Chicago screw and we have a plug
For the breathing tube I used ½’’ id black vinyl tubing. This is a bit stiffer then I would like but I did not want it to crush under vacuum.
The pic here has the tube in directly; I added a right angle fitting so that things would fit better when in the bed. This worked well but does leak so I will be adding a latex gasket around the fitting to prevent air loss at this junction.
For the tube to exit the vac bed I decided to have it go through the frame.
Simply drilled two holes (hole saw) in the pvc frame to allow the tube to pass; then added a hole/gasket in the envelope of the bed (placed to match the frame).